1. Field of the Invention
Chloro-bis(alkylamino)-s-triazine compounds having the following structural formula ##STR1## in which R.sub.1 and R.sub.2 independently represent lower alkyl or cycloalkyl, inhibit the growth of plants and are widely used as herbicides. Especially valuable as herbicides are atrazine(2-chloro-4-ethylamino-6-isopropylamino-s-triazine), simazine (2-chloro-4,6-bis(ethylamino)-s-triazine), and propazine(2-chloro-4,6-bis(isopropylamino)-s-triazine). These compounds are employed both as selective herbicides for weed control among cultivated plants and as soil sterilants for the total elimination of undesired plant growth. Further details with respect to these and other chloro-bis(alkylamino)-s-triazines are set forth in U.S. Pat. No. 2,891,855.
2. Description of the Prior Art
In the process for production of chloro-bis(alkylamino)-s-triazine compounds of the structural formula (I), as defined above, a process stream is obtained comprising a compound as defined by structural formula (I) together with large amounts of undesired tris(alkylamino)-s-triazine by-products as impurities. In order to remove these impurities large amounts of water are employed.
This has resulted in creating a large amount of aqueous alkaline effluent containing a large variety of triazine impurities, including tris(alkylamino)-s-triazines and also a compound of the above structural formula (I), for instance, 2-chloro-4-ethylamino-6-isopropylamino-s-triazine. Thus, prior to the present invention an extractive technique which would allow separation of tris(alkylamino)-s-triazine and chloro-bis(alkylamino)-s-triazine had been highly desired but was unavailable.
U.S. Pat. No. 3,681,335 purports to teach a method for the suppression of tris(alkylamino)-s-triazine in the production of chloro-bis(alkylamino)-s-triazine through adjustment of pH, but this method is not only not being practiced because of the risk of hydrolysis losses but also is basically different because it involves prevention of formation of tris(alkylamino)-s-triazine compounds by immediate removal of any excess alkylamine reactant.